Recently, there is a rapid growth of Internet communications since various Internet Protocol (IP)-based applications have become available. Multiprotocol Label Switching (MPLS) is an evolving standard that is intended for such Internet applications.
Multiprotocol Label Switching (MPLS) is a widely supported method of speeding up IP-based data communication over communication networks, such as asynchronous transfer mode (ATM) networks. As IP and ATM come together, the MPLS concept is to route a packet at the edge of the network and switch the packet in the core of the network. In other words, routers are used at the ingress and egress edges of the network, where their high levels of intelligence can be best used and where their inherent slowness can be tolerated. Switches are used in the core of the network, where they can take advantage of the intelligent routing instructions provided by the routers, and where their inherent speed offers great advantage.
In an MPLS network, an IP data stream enters the edge of the network, and the ingress router reads the full address of the first data packet and attaches a small label in the packet header, which precedes the packet. The ATM switches in the core of the network examine the much-abbreviated label, and switch the packet with much greater speed than if they were forced to consult programmed routing tables associated with the full IP address. All subsequent packets in a data stream are automatically labeled in this manner, and very quickly switched as they have been anticipated.
In the MPLS scheme, a plurality of label switched paths (LSP) between the ingress node and the egress node on the network are provided, and a data packet with a fixed-size label attached is delivered on the plurality of LSPs. The routers at nodes of the MPLS network are called label switching routers (LSR) in this scheme. The label switching routers can deliver the incoming packet on the LSPs by reading the address information of the packet in the fixed-size label. By making use of the MPLS scheme, it is expected that the IP-based data communication over the communication networks can be speeded up and the concentration of traffic load on a specific path of the network can be avoided.
Further, there has been of great interest in that the scheme of MPLS adaptive traffic engineering (often called MATE) has the potential for more effectively optimizing the use of network resources as compared with that in the conventional IP-based communication networks. In order to achieve this scheme, it is desired to provide a data communication network having a capability of selecting a plurality of paths passing through a router at an arbitrary node of the network when transmitting data on the network.
Further, the concept of the MPLS does not rely on the communication medium through which data is transmitted. In the above-described MPLS scheme, data communication may be carried out through any communication media, including an ATM network, a frame relay network, a point-to-point link, etc. In a case of the ATM network, the label provided by the MPLS scheme is attached in the VPI/VCO field of an ATM cell header. The ATM network is a high-speed scheme using the transmission of fixed-size cells and intended for broadband integrated services digital network (B-ISDN) services. The ATM network is currently implemented in various areas of the field and provided with an adequate capability of supporting quality-of-service (QOS) classes for the expected B-ISDN services.
In the existing IP packet-switched network, such as the Internet, the routing of an incoming packet through the network is determined according to the existing routing protocol in a self-controlled manner. For example, the Open Shortest Path First (OSPF) algorithm is a typical one of the routing protocols that have been commonly used. The OSPF algorithm is a link-state routing algorithm that is used to calculate routes based on the number of routers, transmission speed, delays and route cost. When the OSPF algorithm is used as the routing protocol, the shortest path of the packet to its destination router on the network is automatically selected first.
However, the above-mentioned routing protocol, that is, selecting the shortest path on the network first, does not always result in an efficient use of the network resources. For example, when the channel capacity of the link on the selected shortest path is less than the data rate of the incoming packets, the traffic load on the shortest path becomes too heavy, which will cause a congestion condition of the path in the network.
Further, in the case of the above-mentioned routing protocol, a single path for routing the packet to its destination router on the network is automatically selected. It is impossible that the above routing protocol is used to select two or more paths for routing the packet to its destination on the network. Hence, when the above routing protocol is used, it is difficult to disperse the incoming traffic load to the two or more paths within the network.
Accordingly, it is an object of the present invention to provide a novel, useful method and apparatus for selection of paths to route an incoming traffic through a data communication network, which is capable of effectively dispersing the traffic load to the selected paths on the network and effectively optimizing the use of network resources.